Problem: Simplify the following expression: $n = \dfrac{5}{6z} - \dfrac{1}{4z}$
Explanation: In order to subtract expressions, they must have a common denominator. The smallest common denominator is the least common multiple of $6z$ and $4z$ $\lcm(6z, 4z) = 12z$ $ n = \dfrac{2}{2} \cdot \dfrac{5}{6z} - \dfrac{3}{3} \cdot \dfrac{1}{4z} $ $n = \dfrac{10}{12z} - \dfrac{3}{12z}$ $n = \dfrac{10 -3}{12z}$ $n = \dfrac{7}{12z}$